Then you're using something bigger than a Cortex-A55?
Yes I build something using a standard x86_64 (celeron) setup. I heavily experimented with an all arm setup thought. I still find it pretty hard to balance a cheap build that is expandable. I recently lost an OSD and my setup had a consistently high load while recovering.
I don't really like the power consumption of my current setup and am thinking of moving to arm. (I use multiple small HDDs between 1tb and 10tb and have different pools with different redundancys. Am thinking of replacing it with a simple raid or something and 3-4 12tb HDDs with a simple redundancy. Could use minio as s3 replacement and btrfs as fs [I won't use zfs for different reasons] btrfs has snapshots, compression and deduplication so everything I want and need. Never did use rbd over network)
Edit: This is my home setup I'm talking about. At work we got a real setup.
You can even 3D print a nice enclosure, these days.
If you're DIYing, then DIY.
Trying to go lower power doesn't feel worth it, particularly when the hard drives drink so much power.
I feel like I'm spilling the beans sharing this, but ServeTheHome has has an excellent "TinyMiniMicro" series on ~1L size mini-PCs, which are used in businesses a lot. They are much beefier boxes than my little celeron, now often 6 core with way higher clocks. They come with 35W and 65W cpus, but even the couple generations old models still tend to idle at ~10W & otherwise sip power only as demanded[1].
If power is your concern, get rid of your small hard drives. Switch to ARM? Meh.
[1] https://www.servethehome.com/hp-elitedesk-800-g4-mini-tinymi...